Method of washing granular material



Patented Dec. 24, 1929 UNITED STATES ARTHUR JOHN MASON, OF HOMEWOOD, ILLINOIS METHOD OF WASHING GRAN ULAR MATERIAL Application led January 21, 1929. Serial No. 333,923.

This invention relates to improvement-s in the method of washing granular material. As here shown, the invention relates more particularly to the washing of phosphate of lime.

In the process of cleaning or washing natural deposits of bone phosphate of lime in the Tennessee fields, it has been the practice heretofore to treat or wash the same by passing it through a washer, the steps comprising crushing, softening the contained undesired clayey matter, treating it by extensive tossing and tumbling, and finally rejecting the dirty water and procuring a product more than half of which is sand, running from 70 to 75 per cent of bone phosphate of lime. This product was then passed through a drier and sold as brown rock, WellA known in the art. Such a treatment or washing of the product is shown,

for example, in United States Patents Nos. 1,128,874 of February 16, 1916, issued to Hoover and Mason, and 492,262 of February 21, 1893, issued to Beaty.

I have found that by the practice of my invention, I am able to produce a product of higher grade and more value than is produced by such treatment or washing referred to; and my invention contemplates the further and additional treatment hereinafter described.`

In examining the older product carefully, I have found that each grain of the so-called sand, generally has adhering to it a small .amount of indurated clay, silica, and minute phosphate rock particles. This conglomeration is too hard and cemented to be detached by ordinary washing.

In the practice of my invention, I clean or wash the sand before it reaches the drier. I mix with the sand, water not exceeding per cent. of its own weight. I have found that water equal in amount to about 20 per cent by weight of the materials gives a satisfactory mixture. I then agitate the mixture to subject the sand, while thus in the water, to a vigorous rubbing of one particle upon another. I have found that no amount of even prolonged Washing with abundant water as the practice has heretofore existed. will loosen the indurated material as before stated, to the desired degree, as the excessV of water which heretofore has been from 5 to 2O times the weight of the material being treated) acts as a lubricant and the particles do not suthciently abrade one another.

The rubbing may be accomplished by any form of puddling tool, for example, such as now `used in puddling clay in brick-making. I have found that this treatment is well effected by the machine or tool known as a mulcher, which is already in use in this art, for softening the entire product as it comes from the mine before washing. Such a mulcher is shown in the accompanying drawings, in which Figure 1 is a vertical sectional view, and Fig. 2 is a view taken as indicated by the line 2 of Fig. 1.

As shown in the drawings, 10 is a circular plate attached to the shaft A. The rings 12, 14 and 16 are held stationary. The rings 13, 15 and 17 rotate with the shaft A which may be driven from the bevel pinion 18 meshing -with the bevel ring gear 19 on the plate 10,

20, 20. indi-cate radial flattened spokes or paddles connected to the various rings. The various rings, it will be noted, overlap slightly and taper inwardly from the upper edge toward the bottom, so that material fed inside the upper ring will pass on down through the rings, each acting as a funnel for the ring below.

The material may be fed in at the top from a chute indicated by B and may be removed from the bottom plate 10 by means of a suitable plow C.

In the operation of thedevice, the rings attached to the shaft A are driven while others remain stationary. The material is fed in from the top and passes down through the ring by gravity. At it does this, it is agitated by the paddles 20 and in this manner, the material forms, in effect, a series of millstones grinding upon itself. In this manner, practically each particle is abraded and the hardened, cemented undesired foreign matter ground oft'. The particles of bone phosphate are too hard to suer except for a slight abrasion and loss. The sand, when entering this process, appears as a clean sand, merely resembling ordinary building sand. After passing through the process, it appears more like mud, greasy and no longer resembling sand. This last product is then washed with added water and the clean, fine rock passed to the drier.

I have Jfound that by my new process, the normal commercial phosphate rock sand is generall advanced from a 7 3 grade to a 77 grade, t e rejected mud being similar to that rejected in the earlier stages of washing of the older processes, in which the waste runs to' substantially 35 per cent of the bone phosphate of lime.

While I have shown and described certain embodiments of my invention, it is to be understood that it is capable of many modiications. Changes, therefore, in the construction and .arrangement may be made without departing from the spirit and scope of the invention disclosed in the appended claims,

in which it is my intention to claim all novelty in my invention as broadly as possible, inA view of the prior art.

' .What I claim is new, and desire to secure by Letters Patent, is: l

1. The method of treating a granular bone phosphate of lime consisting of first washing the same and then mixing the same with water not exceeding 40 per cent of its own weight and agitating the mixture to cause the grains of material to abrade one another.

2. The method of treating a granular bone phosphate of lime consisting of rst washing the same and then mixing the same with about 20 per cent by weight of water and agitating the mixture to cause the grains of material to abrade one another.

In testimony whereof, I have hereunto set myhand this 14th day of January, A. D.

ARTHUR JOHN MASON. 

